Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
H, W = map(int, input().split())
inf = 101
s = [''] * H
cnt = 0
for i in range(H):
	s[i] = input()
	cnt += s[i].count('.')
d = [[inf] * W for i in range(H)]
from collections import deque
queue = deque([[0, 0]])
d[0][0] = 0

while queue:
	x, y = queue.popleft()
	if x+1 == H and y+1 == W:
		break
	dx, dy = [-1, 0, 1, 0], [0, -1, 0, 1]
	for i in range(4):
		nx, ny = x + dx[i], y + dy[i]
		if 0 <= nx and nx < H and 0 <= ny and ny < W and s[nx][ny] != '#' and d[nx][ny] == inf:
			queue.append([nx, ny])
			d[nx][ny] = d[x][y] + 1

if d[H-1][W-1] == inf:
	print(-1)
else:
	print(cnt-d[H-1][W-1]-1)